Nondestructive testing of defects in adhesive joints

Effect of plasticizer, filler and solvent swell on polyurethane elastomers
Santosh K Gurunath a *, M. Rengasamy b and V. Sivasubramanian a#
a Department of Chemical Engineering, National Institute of Technology Calicut,
Kerala – 673 601, India.
b Department of Petrochemical Technology, Bharathidasan Institute of Technology, Tiruchirappalli -620
024, India.
Email: siva@nitc.ac.in
Abstract
Polyurethane elastomers are developed using different types of isocyanate terminated polyether
based prepolymers (A, B and C) with four types of multifunctional hydroxy derivated curatives (X1, X2,
X3 and X4) and selected processing additives namely plasticizer and filler. The polyurethane elastomers
are developed with a view to utilize them in high performance print roller applications, with improved
strength and solvent resistant characteristics. The properties like pot life, hardness, tensile strength,
modulus, tear strength, compression set, density and solvent resistance of these polyurethane elastomers
are studied in the absence of additives and also in the presence of additives. Among the polyurethane
elastomers prepared, the product obtained from prepolymer C with curative X3 exhibits better strength
properties and solvent resistant characteristics than those from other products. Incorporation of additives
(plasticizer and filler) improves the performance characteristics of polyurethane elastomers. However, the
degree of improvement varies based on the nature of reactants involved.
Keywords : Polyurethane elastomers, Plasticizers and Solvent swell
Introduction
Polyurethanes are available as rigid, flexible and structural foams, elastomers, coatings,
adhesives, casting resins and fibres 1 . These can be manufactured in the wide range of varying densities
from 6 kg/m 3 to 1220 kg/m 3 and polymer stiffness from very flexible elastomers to rigid hard plastics.
Polyurethane has high porosity, low weight to volume ratio, good thermal and acoustic properties, good
resilience, abrasion resistance and oil resistance. This material finds wide industrial and engineering
applications. Polyurethane is a product 2 of the poly addition of an isocynate and an alcohol. Reaction is an
exothermic.
nR – NCO + n HO –R’ → R – [NHCOO]n – R’
There are many kinds of poly isocynates and polyols of different molecular weights and
functionalities are used and each one has its one particular property to give a different product for definite
end use. Polyurethane elastomers are used in many fields like automobile, textile, oil, mining, electronic,
and other engineering industries. There is a very good future of polyurethane elastomers. They are
versatile engineering materials designed to provide properties that are not obtained from conventional
rubbers, metals, and plastics. They have higher oil and solvent resistance and better aging properties than
most general purpose rubbers and plastics. They have greater abrasion and tear resistance than neoprene
or natural rubber, greater load bearing capacity; extensibility and impact character of polyurethane
elastomer are also greater than those of most plastics. They have a wide range of hardness from soft
rubbers to rigid plastics 3-10 . The objective of the present study is to prepare polyurethane elastomer and to
study the performance characteristics.
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